[reaction: see text] The dirhodium tetracarboxylate, Rh2(S-PTAD)4, derived from adamantylglycine, is a very effective chiral catalyst for carbenoid reactions. High asymmetric induction was obtained in Rh2(S-PTAD)4-catalyzed intramolecular C-H insertion (94% ee), intermolecular cyclopropanation (99% ee), and intermolecular C-H insertion (92% ee).

Dirhodium tetrakis((S)-N-(dodecylbenzenesulfonyl)prolinate) (Rh(2)(S-DOSP)(4)) is an effective chiral catalyst for the enantioselective cyclopropenation of alkynes by methyl aryldiazoacetates. [reaction: see text]

[reaction: see text] Rh(2)(S-biTISP)(2)-catalyzed reactions of dimethyl aryldiazomethylphosphonates generate donor/acceptor-substituted rhodium carbenoid intermediates capable of cyclopropanation of styrenes in high yields (85-96%), diastereoselectivity (> or =98% de), and enantioselectivity (76-92% ee).

Supporting InformationGeneral Methods: 1 H NMR spectra were run at either 300, 400, or 500 MHz, and 13 C NMR at either 75 or 125 MHz in CDCl 3 unless otherwise noted. Mass spectral determinations were carried out at 70 eV. Melting points were uncorrected. IR spectra were obtained using a Nicolet Impact series 420 IR. Optical rotations were measured using a Jaso DIP-370 digital polarimeter. Glasswares were flame dried prior to use. Solvent hexanes were distilled over sodium with triglyme and benzophenone. Reactions were carried out under an atmosphere of argon. Elemental analysis performed by Atlantic Microlab, Inc.; Norcoss, Georgia. Column chromatography was carried out on Merck silica gel 60 (230-400 mesh). Commercially available reagents were used without additional purification unless noted. Rh 2 (S-DOSP) 4 (1) was prepared by following the literature procedure. 1 General procedure for Rhodium(II)-Catalyzed Decompositions of MethylPhenyldiazoacetate in the Presence of Alkynes: A mixture of alkyne (2.5 -10.0 equiv) and Rh(II) catalyst (0.01 equiv) in 10 mL of hexane was stirred at room temperature under an argon atmosphere. To this solution was added the methyl phenyldiazoacetate (1 equiv, 0.5 mmol) in 5 mL of hexane via syringe pump over 5 h, and the mixture was then

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